Evolutionary biologist, high altitude expedition leader, developer of the K- Ration, pioneer in the study of human starvation and rehabilitation, architect of the National Science Foundation, discoverer of the relationship between cholesterol and cardiovascular disease, early advocate for the Mediterranean Diet, bestselling cookbook author - all of these titles describe Ancel Keys, whose career spanned seven decades and nearly as many scientific disciplines. Keys's accomplishments alone make him a worthy subject for a full scholarly biography, but his rebellious and bohemian spirit, his academic and personal wanderlust, his eloquence, and his willingness to take risks and build new disciplinary empires in science make his story interesting as well. I propose to write a biography of Ancel Keys (1904-2004), examining his life and science across the twentieth century. Keys's path from studying the evolution of tidal pond fish to examining the effects of human starvation on Conscientious Objectors (COs) during World War Two, to demonstrating the connection between diets rich in saturated fats and cardiovascular disease across the globe not only reveals how individuals from diverse disciplines contributed to the rise of the science of human nutrition and chronic disease epidemiology, but how the military, the church, the food industry, and governments throughout the United States, Europe, Scandinavia, and Asia cooperated to frame these evolving life sciences. Indeed, each period of Keys's life offers insight into the development of new scientific disciplines - human biology;oxygen physiology;nutritional physiology;cardiovascular epidemiology - as well as the popularization of science, the development of scientific foundations, and the evolution of human subject experimentation in the United States.